Tissue relaxation monitoring for optimized tissue stapling

ABSTRACT

A circular stapling device includes a handle assembly including a processor, an adapter assembly including a trocar assembly and a strain gauge assembly, a reload assembly operably secured to the adapter assembly, the reload assembly including a staple cartridge, and an anvil assembly releasably secured to the trocar assembly and moveably positioned relative to the staple cartridge between a spaced position and a clamped position. The processor includes software for determining when tissue clamped between the staple cartridge and the anvil assembly has achieved a predetermined tissue relaxation percent. A method of optimizing tissue relaxation during a stapling procedure includes clamping tissue between an anvil assembly and a reload assembly, calculating a tissue relaxation percent of the clamped tissue, and initiating a stapling sequence when the tissue relaxation percent equals or is less than a predetermined tissue relaxation percent.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date of provisionalU.S. Application No. 63/028,136, filed on May 21, 2020.

FIELD

This disclosure is generally related to powered surgical staplingdevices and, more particularly, to powered surgical stapling devicesthat include software that utilizes strain measurements to optimizestapling and/or cutting of tissue.

BACKGROUND

Powered surgical stapling devices include a handle assembly, an adapterassembly including a proximal portion supported on the handle assembly,and a tool assembly supported on the distal portion of the adapterassembly. The tool assembly often includes a reload assembly and ananvil assembly moveably positioned relative to the reload assembly toclamp tissue therebetween. The stapling device may also include a straingauge for measuring characteristics of tissue being clamped and/orstapled, e.g., tissue thickness, tissue compression, etc., and/orparameters related to staple formation or tissue cutting, e.g., cuttingforce, firing force, etc. Typically, a strain gauge is supported withinthe adapter assembly and is formed from electronics that can besterilized or reprocessed to facilitate reuse of the adapter assembly.Such electronics are costly.

During a stapling procedure, when clamping tissue many surgeons wait aspecified period of time, e.g., fifteen seconds or more, after achievinga predetermined tissue gap between the anvil assembly and the reloadassembly. This waiting period provides the clamped tissue with time torelax, e.g., allows fluid to travel out of the clamped tissue intosurrounding tissue, and is intended to encourage a less traumatic staplefiring. Waiting longer than is necessary for the clamped tissue toachieve an optimum relaxation extends the time of surgery. Conversely,not waiting a sufficient period of time for the tissue to relax canunnecessarily damage the stapled tissue and/or result in staplemalformation.

Therefore, it would be beneficial to have a device for and method formonitoring tissue relaxation and indicating when optimum tissuerelaxation is achieved.

SUMMARY

A circular stapling device includes a handle assembly including aprocessor, an adapter assembly operably secured to the handle assemblyand including a trocar assembly and a strain gauge assembly, a reloadassembly operably secured to the adapter assembly, the reload assemblyincluding a staple cartridge, and an anvil assembly releasably securedto the trocar assembly and moveably positioned relative to the staplecartridge between a spaced position and a clamped position. Theprocessor includes software for determining when tissue clamped betweenthe staple cartridge and the anvil assembly has achieved a predeterminedtissue relaxation percent, i.e., when the clamped tissue is determinedto have stabilized.

In certain aspects of the disclosure, the predetermined tissuerelaxation percent is between about 1% and about 0.5%. The strain gaugeassembly may include a plurality of strain gauges. The software may beconfigured to activate an alert when the predetermined tissue relaxationpercent is achieved. The software may alert the clinician with anaudible, visual, and/or tactile feedback. The software may be configuredto initiate a stapling sequence when the predetermined tissue relaxationpercent is achieved. The software may be configured to activate an alertafter the tissue is clamped for a predetermined time period. Thepredetermined time may be 15 seconds. The software may be configured totake samples of the clamping force at a predetermined sampling rate. Thepredetermined sampling rate may be 400 milliseconds.

A method of optimizing tissue relaxation during a stapling procedureincludes clamping tissue between an anvil assembly and a reloadassembly, calculating a tissue relaxation percent of the clamped tissue,and initiating a stapling sequence when the tissue relaxation percentequals or is less than a predetermined tissue relaxation percent.

In certain aspects of the disclosure, clamping the tissue includesmoving the anvil assembly relative to the reload assembly until apredetermined gap is achieved between the anvil assembly and a staplecartridge of the reload assembly. Calculating the tissue relaxationpercent may include using a 6-tap strain gauge history buffer.Initiating the stapling sequence may occur when the measured tissuerelaxation percent is between about 0.05% and 1%. Initiating thestapling sequence may occur 15 seconds after clamping tissue iscomplete.

Aspects of the method may further include initiating a cutting sequence.The cutting sequence may be initiated at the completion of the staplingsequence. The cutting sequence may be initiated when the tissuerelaxation percent equals or is less than a second predetermined tissuerelaxation percent, or after a predetermined time period has elapsed,whichever occurs first. Initiating the cutting sequence may beautomatic. Initiating the stapling sequence may occur when the tissuerelaxation percent equals or is less than a predetermined tissuerelaxation percent, or after predetermined time elapses, whicheveroccurs first.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects and features of the disclosure are described withreference to the drawings wherein like numerals designate identical orcorresponding elements in each of the several views, wherein:

FIG. 1 is a side perspective view of a surgical stapling deviceincluding an adapter assembly having a strain gauge assembly accordingto aspects of the disclosure;

FIG. 2 is a side perspective view of the adapter assembly shown in FIG.1 with a trocar assembly and strain gauge assembly shown phantom;

FIG. 3 is a side perspective view of a distal portion of the adapterassembly shown in FIG. 2 , with an outer sleeve removed and a tensiongauge support separated from the adapter assembly;

FIG. 4 is a side perspective view of the trocar assembly, and a tensiongauge housing and tension gauge anchor of the strain gauge assembly,shown in FIG. 2 ;

FIG. 5 is a flow diagram of a stapling sequence according to a method ofthe disclosure; and

FIG. 6 is a flow diagram of a processing step of the stapling sequencein the flow diagram shown in FIG. 5 .

DETAILED DESCRIPTION

The devices and methods for optimizing tissue stapling are described indetail with reference to the drawings, in which like reference numeralsdesignate identical or corresponding elements in each of the severalviews. As used herein the term “distal” refers to that portion of thecomponent farther from the user, while the term “proximal” refers tothat portion of the component closer to the user. In addition, the term“clinician” is used generally to refer to medical personnel includingdoctors, nurses, and support personnel. As used herein, the term “about”means that the numerical value is approximate and small variations wouldnot significantly affect the practice of the disclosed aspects of thedisclosure. Where a numerical limitation is used, unless indicatedotherwise by the context, “about” means the numerical value can vary by±10% of the stated value and remain within the scope of the disclosure.

The methods of optimizing tissue stapling described below utilize astrain gauge assembly of a circular stapling device to monitor straingauge data, i.e., clamping force, during a stapling procedure. Moreparticularly, and as will be described in further detail below, softwarein the stapling device uses strain gauge data to calculate a clampingforce and measure the clamping force at a specified sampling rate. Fromthis, a percent change in force between each data sample is calculated.The software then applies a filter by calculating an average percentchange over a specified amount of percent change readings. When thisaverage percent change calculated value is equal to or less than aspecified tissue relaxation percent, the clinician is encouraged toinitiate a firing sequence. If the average percent change value is notequal to or less than the tissue relaxation percent specified valuebefore a predetermined period of time has elapsed, e.g., fifteen seconds(15 s), the clinician is encouraged to initiate the firing sequenceafter the predetermined period of time has passed.

FIG. 1 illustrates a circular stapling device 10 including a handleassembly 12, an elongate body or adapter assembly 14, a reload assembly16 releasably supported on the adapter assembly 14, and an anvilassembly 18 releasably supported for movement in relation to the reloadassembly 16 between an open position (FIG. 1 ) and a clamped position(not shown). Although the methods for optimizing tissue stapling will bedescribed with reference to a circular stapling device, it is envisionedthat the aspects of the disclosure may be modified for use in surgicalstapling devices having alternative configurations.

The circular stapling device 10 is illustrated as an electricallypowered stapling device including an electrically powered handleassembly 12 that may support one or more batteries (not shown). Theadapter assembly 14 translates power from the handle assembly 12 to thereload and anvil assemblies 16, 18, respectively, to staple and cuttissue. Examples of electrically powered stapling devices can be foundin U.S. Pat. Nos. 9,055,943 and 9,023,014, and U.S. Publication Nos.2018/0125495 and 2017/0340351. Alternately, it is envisioned thataspects of the disclosure may be incorporated into a stapling devicethat is configured for use with a robotic system as disclosed in, e.g.,U.S. Pat. No. 9,962,159, and does not include a handle assembly.

The handle assembly 12 of the circular stapling device 10 includes astationary grip 12 a that supports actuation buttons 13 for controllingoperation of various functions of the circular stapling device 10,including, for example, approximation of the reload assembly 16 andanvil assembly 18, firing of staples from the reload assembly 16, andcutting or coring of tissue.

A processor 20 is disposed within the handle assembly 12 and includes oris operably connected to a memory chip 22. The memory chip 22 mayinclude one or more of volatile, non-volatile, magnetic, optical, orelectrical media, such as read-only memory (ROM), random access memory(RAM), electrically-erasable programmable ROM (EEPROM), non-volatile RAM(NVRAM), or flash memory. The processor 20 may be any suitable processor(e.g., control circuit) adapted to perform the operations, calculations,and/or set of instructions described in the present disclosureincluding, but not limited to, a hardware processor, a fieldprogrammable gate array (FPGA), a digital signal processor (DSP), acentral processing unit (CPU), a microprocessor, and combinationsthereof. Those skilled in the art will appreciate that the processor maybe substituted for by using any logic processor (e.g., control circuit)adapted to execute algorithms, calculations, and/or set of instructionsdescribed herein.

The adapter assembly 14 includes a proximal portion 14 a that can bereleasably coupled to the handle assembly 12. The reload assembly 16includes a proximal portion 16 a that is releasably coupled to a distalportion 14 b of the adapter assembly 14. A staple cartridge 24 issupported on a distal portion 16 b of the reload assembly 16 andsupports a plurality of surgical staples (not shown). A trocar assembly26 is supported within the distal portion 14 b of the adapter assembly14 and extends through the reload assembly 16. The trocar assembly 26includes a trocar member 28 for releasably securing and positioning theanvil assembly 18 relative to the reload assembly 16.

FIGS. 2-4 illustrate a strain gauge assembly 30 supported within thedistal portion 14 b of the adapter assembly 14 (FIG. 2 ) and a trocarassembly 40 received through and supported by the strain gauge assembly30. The strain gauge assembly 30 is positioned between the trocarassembly 40 and the reload assembly 16. With the strain gauge dataprovided by the strain gauge assembly 30, the clamping force between thestaple cartridge 24 of the reload assembly 16 and the anvil assembly 18can be calculated. The trocar assembly 40 releasably secures the anvilassembly 18 (FIG. 1 ) to the circular stapling device 10, and operatesto advance and retract the anvil assembly 18 relative to the reloadassembly 16. The software in the handle assembly 12 uses the straingauge measurements to determine the clamping force over time. As will bedescribed in further detail below, tissue relaxation occurs when theclamping force, i.e., the force on the tissue, stabilizes.

The strain gauge assembly 30 includes a tension gauge housing 32, atension gauge anchor 34, and a tension gauge support 36 (FIG. 3 ). Aplurality of strain gauges 38 are supported on an extension portion 32 a(FIG. 4 ) of the tension gauge housing 32. For a detailed description ofan exemplary strain gauge assembly, please refer to U.S. patentapplication Ser. No. 16/809,023, filed Mar. 4, 2020. Although shown asthe strain gauge assembly 30, it is envisioned that the methods of thedisclosure may be modified for use with any strain gauge assembly.

FIG. 5 illustrates a flow diagram of a stapling procedure for optimizingtissue stapling according to aspects of the disclosure. Initially,tissue to be stapled (not shown) is positioned between an anvilassembly, e.g., the anvil assembly 18 (FIG. 1 ), and a staple cartridge,e.g., staple cartridge 24 (FIG. 1 ) of a reload assembly, e.g., reloadassembly 16 (FIG. 1 ). The anvil assembly is then approximated towardsthe reload assembly to clamp the tissue between the anvil assembly andthe staple cartridge of the reload assembly. The anvil assembly isapproximated towards the reload assembly until a predetermined clamp gapis achieved between the anvil assembly and the staple cartridge.

Strain gauge data provided by a strain gauge assembly, e.g., straingauge assembly 30 (FIG. 2 ), is used to calculate a tissue relaxationpercent, or more particularly, the percent change in the clamp forcebetween two sample points. Tissue relaxation occurs when the compressedfluid within the clamped tissue has been able to flow into adjacenttissue, i.e., the clamping force stabilizes. Tissue relaxation isdetermined to have occurred when the tissue relaxation percent equals oris less than a predetermined tissue relaxation percent, typically0.5-1.0%, or fifteen seconds have elapsed, whichever occurs first. Inaspects of the disclosure, the software is configured to alert theclinician, through audio, visual, and/or tactile feedback, when optimumtissue relaxation has occurred and to initiate a stapling sequence. Incertain aspects of the disclosure, the stapling procedure may beinitiated at any time after the anvil assembly and staple cartridgeachieve the clamp gap distance. It is also envisioned that the softwaremay be programmed to automatically initiate the stapling sequence uponeither the tissue relaxation percent being achieved, or 15 secondselapsing.

Following the stapling sequence, a tissue cutting or coring sequence isinitiated. The cutting sequence may be automatic, or may be manuallyinitiated by the clinician. The cutting sequence may be initiatedsimultaneously with the stapling sequence, directly following thecompletion of the stapling sequence, or after a subsequent time period.

In certain aspects of the disclosure, tissue relaxation optimizationsimilar to that of the tissue relaxation optimization described abovecan also be used prior to initiation of the cutting sequence to minimizetissue damage during cutting/coring of the stapled tissue. In thismanner, subsequent to completion of the stapling sequence and prior tothe initiation of the cutting sequence, the software in the handleassembly calculates a tissue relaxation percent from the strain gaugedata provided by the strain gauge assembly. As with the staplingsequence, once the tissue relaxation percent is equal to or less than apredetermined tissue relaxation percent, or a predetermined time periodhas elapsed, whichever occurs first, the clinician is alerted that thecutting sequence may be initiated. It is envisioned that the cuttingsequence may be initiated automatically.

In a further attempt to optimize tissue stapling, it is envisioned thatthe strain gauge assemblies may be used in combination with the softwareto monitor the clamping forces during tissue clamping. In the event theclamping forces exceed a predetermined threshold, the software canreduce the speed at which the tissue is being clamped, or stop clampingaltogether until the clamping force has fallen below the threshold.

FIG. 6 is a flow diagram detailing the tissue relaxation optimizationprocedure. Although shown using a 6-tap strain gauge history buffer,which is updated at a specified sampling rate, it is envisioned thatmore or less than a 6-tap strain gauge history buffer may be utilized.In one aspect of the disclosure, the sampling rate is 400 millisecondsintervals.

After the buffer fills, consecutive strain gauge values are subtractedto calculate the differential change in force and then divided by theprevious absolute strain gauge value to determine the percent change inforce applied to tissue. This results in five (5) delta percent valueswhich are then averaged. At the next time period, all values in thebuffer are shifted down and the new value is placed in the SGFt0 slot.In this manner, only the last five values are used in the calculation.When a new calculation is done, the oldest value is dropped and does notform part of the new calculation. When the averaged delta percent valuesare less than or equal to a specified tissue relaxation percent, thetissue is determined to be relaxed and the user is encouraged toinitiate the firing. As noted above, in certain aspects of thedisclosure, at a tissue relaxation percent of between about 0.5% andabout 1.0%, tissue is deemed to be sufficiently stabilized, and nofurther significant change in force is likely.

The 6-tap strain gauge history is SGFt5, SGFt4, SGFt3, SGFt2, SGFt1,SGFt0.

The delta percentages (DP) are calculated as follows:

$\begin{matrix}{{{DPt}\mspace{11mu} 4} = \frac{{{SGFt}\mspace{11mu} 5} - {{SGFt}\mspace{11mu} 4}}{{SGFt}\mspace{11mu} 5}} \\{{{DPt}\mspace{11mu} 3} = \frac{{{SGFt}\mspace{11mu} 4} - {{SGFt}\mspace{11mu} 3}}{{SGFt}\mspace{11mu} 4}} \\{{{DPt}\mspace{11mu} 2} = \frac{{{SGFt}\mspace{11mu} 3} - {{SGFt}\mspace{11mu} 2}}{{SGFt}\mspace{11mu} 3}} \\{{{DPt}\mspace{11mu} 1} = \frac{{{SGFt}\mspace{11mu} 2} - {{SGFt}\mspace{11mu} 1}}{{SGFt}\mspace{11mu} 2}} \\{{{DPt}\mspace{11mu} 0} = \frac{{{SGFt}\mspace{11mu} 1} - {{SGFt}\mspace{11mu} 0}}{{SGFt}\mspace{11mu} 1}}\end{matrix}$

The Percent Reduction (PR) is determined by averaging the DeltaPercentages as follows:

${{PRt}\mspace{11mu} 0} = \frac{{{DPt}\mspace{11mu} 4} + {{DPt}\mspace{11mu} 3} + {{DPt}\mspace{11mu} 2} + {{DPt}\mspace{11mu} 1} + {{DPt}\mspace{11mu} 0}}{5}$

As noted above, if the predetermined tissue relaxation percent is notdetected within 15 seconds, the tissue is determined to be relaxed andthe user is encouraged to initiate firing.

The above described devices and methods allow clinicians to make a moreinformed decision about whether clamped tissue has relaxed to a pointwhere the tissue damage is minimized. The software also allows forcollection of tissue relaxation data which can be analyzed later tobetter understand how tissue behaves after clamp and before firing in areal firing.

Persons skilled in the art will understand that the devices and methodsspecifically described herein and illustrated in the accompanyingdrawings are non-limiting and exemplary. It is envisioned that theelements and features illustrated or described in connection with oneaspect of the disclosure may be combined with the elements and featuresof another without departing from the scope of the disclosure. As well,one skilled in the art will appreciate further features and advantagesof the disclosure based on the above-described aspects. Accordingly, thedisclosure is not to be limited by what has been particularly shown anddescribed, except as indicated by the appended claims.

What is claimed is:
 1. A circular stapling device comprising: a handleassembly including a processor; an adapter assembly operably secured tothe handle assembly and including a trocar assembly and a strain gaugeassembly; a reload assembly operably secured to the adapter assembly,the reload assembly including a staple cartridge; an anvil assemblyreleasably secured to the trocar assembly and moveably positionedrelative to the staple cartridge between a spaced position and a clampedposition; and a memory including instructions stored thereon, which whenexecuted by the processor cause the circular stapling device to: capturea plurality of strain gauge value measurements at a predeterminedsampling rate for tissue clamped between the staple cartridge and theanvil assembly; determine a differential change in force based onsubtracting consecutively sampled strain gauge value measurements fromeach other; determine a percentage change in force based on dividing thedifferential change in force by a previous strain gauge measurementvalue; determine a percent reduction based on averaging the percentchange in force; determine if the percent reduction is equal to or lessthan a predetermined threshold value, wherein the predeterminedthreshold value indicates a tissue relaxation; and initiating a staplingsequence when the percent reduction is equal to or is less than thepredetermined threshold value.
 2. The circular stapling device of claim1, wherein the predetermined threshold value is between about 1% andabout 0.5%.
 3. The circular stapling device of claim 1, wherein thestrain gauge assembly includes a plurality of strain gauges.
 4. Thecircular stapling device of claim 1, wherein the instructions, whenexecuted by the processor, further cause the circular stapling deviceactivate an alert when the predetermined threshold value is achieved. 5.The circular stapling device of claim 4, wherein the instructions, whenexecuted by the processor, further cause the circular stapling device toalert a clinician with an audible, visual, and/or tactile feedback. 6.The circular stapling device of claim 1, wherein the instructions, whenexecuted by the processor, further cause the circular stapling device toinitiate a cutting sequence at a completion of the stapling sequence. 7.The circular stapling device of claim 1, wherein the instructions, whenexecuted by the processor, further cause the circular stapling device toactivate an alert after the tissue is clamped for a predetermined timeperiod.
 8. The circular stapling device of claim 7, wherein thepredetermined time is 15 seconds.
 9. The circular stapling device ofclaim 1 wherein the predetermined sampling rate is 400 milliseconds. 10.A method of optimizing tissue relaxation during a stapling procedure,the method comprising: clamping tissue between an anvil assembly and areload assembly; capturing a plurality of strain gauge valuemeasurements at a predetermined sampling rate for tissue clamped betweenthe reload assembly and the anvil assembly; determining a differentialchange in force based on subtracting consecutively sampled strain gaugevalue measurements from each other; determining a percentage change inforce based on dividing the differential change in force by a previousstrain gauge measurement value; determining a percent reduction based onaveraging the percent change in force; and determining if the percentreduction is equal to or less than a predetermined threshold value,wherein the predetermined threshold value indicates a tissue relaxation;and initiating a stapling sequence when the percent reduction equals oris less than the predetermined threshold value.
 11. The method of claim10, wherein clamping the tissue includes moving the anvil assemblyrelative to the reload assembly until a predetermined gap is achievedbetween the anvil assembly and a staple cartridge of the reloadassembly.
 12. The method of claim 10, wherein calculating thedifferential change in force includes using a 6-tap strain gauge historybuffer.
 13. The method of claim 10, wherein initiating the staplingsequence occurs when the percent reduction is between about 0.5% and 1%.14. The method of claim 10, wherein initiating the stapling sequenceoccurs 15 seconds after clamping tissue is complete.
 15. The method ofclaim 10, further including initiating a cutting sequence.
 16. Themethod of claim 15, wherein the cutting sequence is initiated at acompletion of the stapling sequence.
 17. The method of claim 16, whereinthe cutting sequence is initiated when the percent reduction equals oris less than a second predetermined threshold value, or after apredetermined time period has elapsed, whichever occurs first.
 18. Themethod of claim 15, wherein initiating the cutting sequence isautomatic.
 19. The method of claim 10, wherein initiating the staplingsequence occurs when the percent reduction equals or is less than apredetermined threshold value, or after predetermined time elapses,whichever occurs first.